The present invention relates to a low dead space easily cleaned manifold for detaching a container of a chemical delivery system, and in particular to an apparatus for delivering high-purity or ultra-high purity chemicals to a use point, such as a semiconductor fabrication facility or tool(s) for chemical deposition. Although the invention may have other applications, it is particularly applicable in semiconductor fabrication.
Semiconductor manufacturers require chemicals having at least a high-purity for production processes to avoid defects in the fabrication of semiconductor devices. The chemicals used in the fabrication of integrated circuits usually must have an ultra-high purity to allow satisfactory process yields. As integrated circuits have decreased in size, there has been an increase in the need to maintain the purity of source chemicals.
One ultra-high purity chemical used in the fabrication of integrated circuits is tetrakis(dimethylamido)titanium (TDMAT). TDMAT is used widely in integrated circuit manufacturing operations, such as chemical vapor deposition (CVD) to form titanium and titanium nitride films, vias and barrier layers.
Integrated circuit fabricators typically require TDMAT with 99.99+% purity, preferably 99.999999+%(8-9's+%) purity. This high degree of purity is necessary to maintain satisfactory process yields. It also necessitates the use of special equipment to contain and deliver the high-purity or ultra-high purity TDMAT to CVD reaction chambers.
High-purity chemicals and ultra-high purity chemicals, such as TDMAT, are delivered from a bulk chemical delivery system to a use point, such as a semiconductor fabrication facility or tool(s). A delivery system for high-purity chemicals is disclosed in U.S. Pat. No. 5,590,695 (Seigele, et al.) which uses two block valve assemblies 76 and 91, but not to facilitate rapid clean disconnection. (Related patents include U.S. Pat. Nos. 5,465,766; 5,562,132; 5,607,002; 5,711,354; 5,878,793 and 5,964,254.) The system comprises: a block valve assembly housing a low pressure vent valve and a carrier gas isolation valve, while the other block valve assembly houses a container bypass valve and a process isolation canister bypass valve. The block valve assemblies are not in series nor are they used for disconnect of a container from a manifold.
Solvent purging systems for removal of low vapor pressure chemicals from process conduits are disclosed in U.S. Pat. No. 5,964,230 and U.S. Pat. No. 6,138,691. Such systems may add additional complexity to purging and increase the amount of materials which must be disposed of.
Low dead space couplings are known, such as U.S. Pat. No. 6,161,875.
TDMAT is considered a low vapor pressure, high purity chemical by the semiconductor industry, and thus presents special problems when breaking a process line or changing out a process container where the line must be cleaned prior to such detachment. Significant time delays in cleaning down a line or conduit are a disadvantage in the throughput of a wafer processing facility, where expensive tools and large batch processing of expensive wafers, each containing hundreds of integrated circuits require fast processing and avoidance of significant or lengthy offline time for cleaning or changeout of process containers or vessels.
The Present invention is more specifically directed to the field of process chemical delivery in the electronics industry and other applications requiring low vapor pressure, high purity chemical delivery. More specifically, the present invention is directed to apparatus for the cleaning of process chemical delivery lines, containers and associated apparatus, particularly during changeout of process chemical or process chemical containers in such process chemical delivery lines, quickly and thoroughly, when processing with low vapor pressure, high purity chemicals.
Evacuation and gas purge of process chemical lines have been used to remove residual chemicals from delivery lines. Both vacuum draw and inert gas purge are successful in quickly removing high volatility chemicals, but are not effective with low volatility chemicals. Safety is a problem when extracting highly toxic materials.
Use of solvents to remove residual chemicals has been suggested to remove low vapor pressure chemicals from process lines when the lines need to be disconnected such as for replacement of a vessel or container for either refill or maintenance. However, solvent systems can be complex and require a source of solvent and a means to handle the contaminated solvent after it has been used for its cleaning function.
Additional patents directed to effective chemical removal are U.S. Pat. No. 6,345,642 and U.S. Pat. No. 6,418,960.
The present invention overcomes the drawbacks of the prior art in purging and cleaning chemical process lines for low vapor pressure chemicals without the requirements of lengthy purge cycles of pressurized gas and vacuum, as will be more fully set forth below.